Toward Label-Free Selective Cell Separation of Different Eukaryotic Cell Lines Using Thermoresponsive Homopolymer Layers.

Ultrathin thermoresponsive poly(di(ethylene glycol) methyl ether methacrylate) (PDEGMA) homopolymer layers are reported as a novel platform for label-free temperature-stimulated cell separation from a coculture of eukaryotic cell lines. Pancreatic tumor cells (PaTu 8988t) and fibroblasts (NIH 3T3) were shown to attach and proliferate on PDEGMA layers with a dry thickness of 5 ± 1 nm at 37 °C. After the cell medium cooled to below the lower critical solution temperature (LCST), PaTu 8988t cells showed a significantly decreased cell area. By contrast, there was no significant change in cell area for NIH 3T3 cells, while they still exhibited lamellipodia and filopodia. PaTu 8988t cells could be detached at 22 °C after flushing gently with the cell medium, while negligible cell detachment was observed for NIH 3T3 cells under identical conditions. This significant difference between PaTu 8988t and NIH 3T3 was due to the different cell adhesion on the culture-medium-derived protein covering the PDEGMA layer. Thus, cell separation from a coculture was achieved successfully by cooling the cell medium to 22 °C, resulting in the desorption of 95 ± 6% of PaTu 8988t cells, while the NIH 3T3 cells remained adherent. Our findings provide an effective, label-free, rapid, and simple approach, exploiting a thermoresponsive homopolymer layer to separate and enrich or isolate cells from mixed cell populations for basic biological research, medical diagnostics, tissue engineering, and cell therapy.